Account of an Hydraulic Orrey. 415 
IX. The magnetism produced by electricity, though with the 
same conductors it increases with the heat, as | mentioned in 
my last paper; yet with different conductors I find it follows 
a very different law. Thus, when a chain is made of different 
conducting wires, and they are placed in the same circuit, they 
all exhibit equal magneti¢ powers, and take up equal quantities 
of iron filings. So that the magnetism seems directly as the 
quantity of electricity which they transmit. And when in a 
highly powerful Voltaic battery, wires of the same diameters and 
lengths, but of which the best conducting is incapable of wholly 
discharging the battery, are made, separately and successively, 
to form the circuit, they take up different quantities of iron filings, 
in some direct proportion to their conducting nagers 
Thus. in one experiment, two inches of wire of 5}, of an inch 
being used, silver took up 32 grains, copper 24, platinum 1], 
and iron 8.2. 
LXXXIV. Account of an Hydraulic Orrery on an improved 
Principle of Motion. By Mr. C. A. Bussy. 
To Dr. Tilloch. 
Sir, — Ix pursuance of the suggestion of my much-respected 
friend, the venerable Dr. Hutton, I am induced to communicate 
to the public a short account of an improved principle of mo-~ 
tion, adopted in an invention of mine, the hydraulic orrery, which 
has been so fortunate as to meet the particular approbation of 
many of our most distinguished philosophers. 
About three years past I was engaged, during my stay at 
New-York, in a course of experiments to determine the resistance 
opposed to solid bodies of various forms in their passage through 
fluids. To perform thesein the most simple and effectual man- 
ner, I provided a large circular bason or reservoir, and placed 
therein, near the circumference, any floating vessel that hap-« 
pened to be the subject of trial. This vessel was connected by 
an arbor to a floating centre, held in its place by a small shaft 
passing through it, and erected perpendicularly from the bottom 
of the reservoir. ‘The bottom of the floating vessel was pierced, 
and a syphon, which it carried, being soldered into the aper- 
ture, rose from it, and extending over the circumfereuce of the 
reservoir, its other extremity depended in air at a lower level 
than the surface of the water. This outer leg of the syphon was 
closed at the bottom ; but a minute lateral aperture, resembling 
a very small finger- -hole of a flute, being made, the water spouted 
through 
